Prop questions for 502 Python Nautique

[2001 Python]

Owner of a 2001 Sport Nautique equipped with a 502 Python motor and I'd like to replace the factory prop with a Acme... looking for some real world experience if anyone has any.


Stock prop is a 14x18 RH... the boat runs about 51 mph at 4900 to 5000 rpm, boat has 170 hrs on it.

The holeshot is good and the boat pulls to max mph smooth, just feel I should be getting a harder hit and more topend considering the power.

I spoke with Jim at Acme and explained my desire, he recommended the 380... 13.5 x 17 .105 cup

I know these boats are fairly rare, but figured I'd give it a shot to see if anyone here has done this before and perhaps run this particular prop, or has one to recommend.

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

UPDATE: *mph measured with Garmin gps*

1st - I pulled the plugs and they were horrible... all gapped to .028 when they should've been .045, standard when the should've been projected tip plugs and the wrong heat range.

Replaced the plugs with the correct NGK's and big difference. Boat Idled smoother, noticeable sharpness in throttle response but Max rpms remained the same.

Max top speed remained unchanged with the stock prop.

2nd - Replaced stock prop with Acme 380... slight increase in the holeshot, but not enough to make me feel like it was worth while. Max top speed increased by a solid 3 mph. Max rpm seems pegged at 5,000, where the stocker would float between 4,900 - 5,000

Think it needs more cup.

I was really hoping for more with this prop change.


3rd - Not completed yet... moving all batteries (3) to the back of the boat.

Pictures for those interested.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Second UPDATE

By the end of this past season I had managed to move all 3 batteries to the back of the boat under the rear hatch opposite the driver... almost 200 lbs of batteries in a custom enclosure.

Made a noticeable difference in the way the boat handles and also leveled the way it sat in the water, always listed to the right by about a 1".

The nose rose out of the water a solid 2 inches sitting unloaded. Hole shots were much improved as was plane time, not that it wasn't a beast before that.

Should have updated this in the early fall but forgot.

Going to try a different prop in the spring, but have not decided which on just yet.




Third UPDATE

Over the holiday weekend, I had my boat loaded with people and during a full throttle blast, I noticed some cavitation. It's only present when the boat is loaded down and wont do anything like that during normal use.

The fact that the Acme 380 prop seemed a bit underwhelming from the start, prompted me to call up Jim at Acme again and see if I could re-prop to something better suited to my combo.

He said that I really need more surface area and cup, considering I was getting cavitation on the 380 prop under heavy load. So he wants me to try a one off prop, he's making me a 14x17 with .165 cup ... in a effort to bring the rpm down a little off redline at WOT and eliminate cavitation under heavy load.

Should have the new prop in the boat and tested by this up coming weekend, will update post when I do.

[rossrips7]

No real world experience but 51 on a nautique is pretty darn fast! That's impressive. Has anyone seen the sv 211 that is modded out on eBay that will supposedly run 76? That thing is built.


Sent from my iPhone using PLANETNAUTIQUE mobile app

[Treybizttu]

So I searched for the 211 you were talking about... Holy crap that's awesome.

http://www.ebay.com/itm/2008-Correct...m=112009632368

[core-rider]

So I searched for the 211 you were talking about... Holy crap that's awesome.

http://www.ebay.com/itm/2008-Correct...m=112009632368

All those pics and not a single shot of the engine they are basically selling... -_- Also find it funny they replaced the gauges and couldn't get a speedometer that read above 50MPH. Heck my factory 2003 gauge reads 50MPH!!! Extending the trailer for I can only assume to protect the rigging that doesn't even extend past the platform. I don't understand throwing all that money into it when it won't be a good go-fast boat or ski boat now.

To answer the OP questions... It's unclear to me, are you wanting more top-end as well as low-end? The prop ACME has recommended will probably make some difference down low, but I don't know if it would be enough to justify the expense.

[Miljack]

To the OP, I had a Python Pro Air (this hull is the "TWC" hull with lifting strakes so a little different), replaced the stock 14 x 18 with the 380. Pulled "redline" on the prop, about the same top end as you, how were you measuring the speed? If it wasn't GPS it's probably off a little. My boat had a tower, racks, etc..
With the slight reduction gear, the 380 is the most versatile. If you want more acceleration/pulling power, stay with a "14" prop (think ACME 380 is 13.7"), and reduce the pitch, but you'll need to make sure the engine doesn't over rev. Not sure you'll get much more top end unless you decide to modify the engine to pull higher than 5,000 rpm...

[2001 Python]

Measured speed with my Garmin Nuvi gps unit from my car.

The platform is Sport, so no ballast tanks, tower or whatnot... nice and light. I believe redline to be 5200 on these motors, yet she barely gets to 5000 on the stock prop.

Jim at Acme said I should pick up a few more mph due to the efficiency of their props and the 380 should provide a better hole shot. Guess I'm looking to confirm with real world.

Jim said the stock 14" prop on the Python equipped boats is actually closer to 13.5" and that their 380 is equal to stock and the pitch change is a little more aggressive to get more bite in the water down low. Also said depending on where the max rpm lands with the 380 prop, that I should make adjustments to cup of the prop and not pitch or size, seeing as I don't run ballast.

Increase the cup of the prop to bring down rpms (if redlining)
Decrease cup to raise rpm

[Miljack]

Make sure you have good plugs in the Python, I seem to remember I had good luck with the AC marine plugs, the 502 likes the "projected" (can't remember exactly what they call them), and chances are if you're not the original owner, the "stock" prop may have been repaired at some point which will vary the pitch and maybe even the diameter. My experience with the 380 vs the "stock" OJ, was the 380 did have better "bite" out of the hole, and a little better top end.
My observation of the tower, etc, is more on the aero side, not weight.
The cup will change the RPM around 100-150 rpm or so with each adjustment, it's a very fine tuning tool.
I don't know if the Sport or Pro hull is better on top end, the Sport hull maybe keeps pushing the bow down? The Sport *may* run faster top end with a little ballast in the trunk...

[2001 Python]

Thanks Miljack, your experience is very much appreciated and valued.

You echoed much of what Jim at Acme gave for advice and that is comforting. So just minutes ago I place the order for my new Acme 380 prop and we shall see if I get a noticeable improvement.

I'm glad you brought up the sparkplugs, I had forgot to even check them... to the top of the list they go.

The hull does keep the nose down and I've been toying with the idea of moving the 3 batteries from up in the nose to the storage area under the sundeck. At just off idle speed the nose of the boat will get spray even with the smallest of waves, moving 120 lbs of battery out back will only help.

I will do these corrections one at a time to see which has what for impact.

[2001 Python]

Update in op.

[surroundsound64]

Such a sweet boat. Keep us updated.

[tbateman40]

Sweet boat man! I have PAN with the 502 python. I'm currently running the stock 14x18 prop. My top speed is 51mph on a good day. I've been thinking about ordering the ACME 380 prop like you did. Kind of a bummer that your not too impressed with yours but thanks for the updates!

[Miljack]

2001 Python thanks for the updates, but more cup will reduce your top end RPM. What are you looking to achieve on top end? Your hull will need ALOT more HP to pick up a few mph...
If you want more HP, you're going to have to do some engine mods, and that will start to get pricey...I noticed that the Python engine always ran rich, and a guy @ PCM told me they fattened up the fuel curve to protect that engine...To change it you'll have to get intimate with the MEFI controller, and learn to program it...

[sweepyboy]

I have a 380 ACME on my 2000 SN. 13.5 RH 17.5 x 1.125 4 blade. Might have a little more out of the hole. Top speed on GPS 54. I have had it on my boat since 2010.

[2001 Python]

Bumpski.... for third update in original post.

[Crabman]

Sorry to bring up an old thread, but what was the best prop you found for top end? Was the 14x17 with .165 cup the way to go? Recently purchased a Ski with the Python in it and would like to get it re-proped.